Enhanced Solar CO2 Photoreduction to Formic Acid by Platinum Immobilization on Bipyridine Covalent Triazine Framework with Defects

The immobilization and structural analysis of platinum nanoparticles on a nitrogen-rich, bipyridine-containing covalent triazine framework (bpyCTF) having structural defects are disclosed by taking advantage of 15N solid-state nuclear magnetic resonance measurements at natural 15N isotope abundance and X-ray photoelectron spectroscopic analyses. The photocatalyst (Pt@bpyCTF) with structural defects reduces CO2 to formic acid (FA) at a rate of 152 µmol h-1g-1 and a selectivity higher than 95% over CO and H2 in water under simulated solar light. The presence of amine defects and the immobilization of Pt cause improvement in the photocurrent density and CO2 capture capacity (?8% by weight) despite the moderate surface area (0.54 cm3 g-1)of the photocatalyst. Theoretical models and density functional theory calculations are employed to investigate the possible CO2 reduction reaction (CO2RR) mechanisms. Considering the exceptional CO2 capture capacity and high FA production using only CO2-bubbled water, this work highlights the great potential of nitrogen-rich CTFs for photocatalyzed CO2RRs under green conditions.